Pisa Syndrome

‘Not long after I received my diagnosis, I first heard the label ‘Pisa Syndrome’ as I sat in the eye doctors exam chair. It had been confirmed, the reason I still couldn’t see to read with my new bifocals was because I needed Prism to be able to read. The doctor says I am seeing double…I am bothered by his declaration. because I don’t see two distinct things. It is just that things are so blurry that a magnifying glass is of no help. Thus, I learn two new phrases: ‘convergence insufficiency’ &’Pisa Syndrome.’

The doctor and his assistant were commenting how I had the lean to one side. They said they knew they went together, but they weren’t sure which one caused the other

Since then, I have had three separate prescriptions for prism lenses. Having cataracts removed allowed me to quit the juggling act with two pair of glasses. If I tried to walk with the prisms on, it would cause me to stumble. Well, it still does make me stumble, but I don’t have too fumble for the other glasses

I found and article from  The Lancet / Neurology

Pisa syndrome is defined as a reversible lateral bending of the trunk with a tendency to lean to one side. It is a frequent and often disabling complication of Parkinson’s disease, and has also been described in several atypical forms of parkinsonism …….. Although no consistent diagnostic criteria for Pisa syndrome are available, most investigations have adopted an arbitrary cutoff of at least 10° of lateral flexion for the diagnosis of the syndrome. Pathophysiological mechanisms underlying Pisa syndrome have not been fully explained. One hypothesis emphasizes central mechanisms, whereby Pisa syndrome is thought to be caused by alterations in sensory–motor integration pathways; by contrast, a peripheral hypothesis emphasizes the role of anatomical changes in the musculoskeletal system………

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PD is the second most common neurodegenerative disease and is characterized by bradykinesia, resting tremor, rigidity, and postural instability.²⁴ It is a progressive, lifelong, and so far incurable disorder causing significant reduction of quality of life and increasing health care burden. Besides aforementioned classical motor symptoms, additional aggravating conditions include postural abnormalities, which are quite common in this population. According to the results of a retrospective observational study, a third of patients with PD had a deformity of their limbs, neck, or trunk. Parkinson described distinctive stooped or bent posture of patients with PD. Nevertheless, significant proportion of patients exhibit more severe postural abnormalities or spinal alignment, leading to significant disability. These severe deformities include PS, camptocormia, scoliosis, and antecollis.  It is noteworthy that most of the patients present with a combination of postural deformities. The underlying pathophysiology of these deformities is largely unknown, and their management remains a challenge/

Pathophysiology

The pathophysiological mechanisms underlying PS in PD patients have not been fully explained. Two different hypotheses have been proposed: 1) central hypothesis consider PS as a consequence of basal ganglia dysfunction along with altered sensory–motor integration, and possibly exacerbation by dopaminergic treatment; 2) according to the peripheral hypothesis, PS occurs primarily due to an alteration of the musculoskeletal system, such as myopathy of the paraspinal muscles and soft tissue changes (Figure 1).^27,32

Postural control depends on vestibular, visual, and somatosensory information. For proper postural control, all these components should act in highly harmonized, synchronous, and orchestral manner. Balance impairment in PD has recently been related to altered sensory–motor integration processing.⁴² Proprioception provides highly accurate information that helps to maintain body verticality. Several studies confirmed abnormality in proprioceptive function in PD patients. Vaugoyeau and Azulay⁴³ showed that PD patients, unlike healthy subjects, were unable to maintain the vertical trunk orientation without visual compensation and were following the oscillations of the supporting platform, whereas the control subjects kept their body upright when deprived of visual cues and vestibular information. Perception of verticality is essential for postural control. Pereira et al⁴⁴ showed that perception of verticality is affected in PD patients. This abnormal vertical perception together with disturbed processing of graviceptive pathways is associated with postural instability. Based on these results, Scocco et al⁴⁵ investigated subjective visual verticality in PD patients with and without PS, and compared them with healthy controls. They found that the subjective visual verticality was altered in PD patients with and without PS when compared to healthy controls. The authors concluded that altered subjective visual verticality cannot be explained by intrinsic lateral deviation in PS patients, yet it must be secondary to either primary perceptual dysfunction or alterations of internal models of verticality. Until recently, it was thought that vestibular dysfunction is not involved in the pathogenesis of postural deformities affecting PD patients.⁴⁶ However, recent investigation by Vitale et al⁴⁷ refuted this hypothesis. They evaluated vestibular function in eleven PD patients with lateral trunk flexion and in eleven age-, sex-, and disease duration-matched patients without lateral trunk flexion. A peripheral, unilateral vestibular hypofunction was identified in all patients with lateral trunk flexion. The vestibular hypofunction was ipsilateral to the leaning side and contralateral to the most affected parkinsonian side in all the patients. In the control group, seven subjects had no vestibular signs and four subjects had unilateral vestibular hypofunction without clinically evident lateral trunk flexion. Interestingly, two of the latter patients subsequently developed lateral trunk flexion ipsilateral to the vestibular deficit and contralateral to the side most affected by PD.

Diagnosis and clinical presentation

There is no consensus on the diagnostic criteria for PS. Initially, Bonanni et al²⁹ proposed the following definition for lateral axial dystonia: more than 15° lateral flexion of the trunk, increasing during walking, not present when supine, and in the absence of any mechanical restriction to trunk movement (ie, degenerative spinal disease), with continuous electromyographic activity in the lumbar paraspinal muscles ipsilateral to the bending side. Doherty et al²⁷ deviated from definition by Bonanni et al²⁹ and proposed that a diagnosis of PS requires at least 10° lateral flexion, which can be completely alleviated by passive mobilization or lying in a supine position. A reason for this deviation was that the pathophysiological mechanism of PS in PD patients may not be completely dystonic and should not require electrophysiological studies to define it.

PS can develop in acute (rapid deterioration within few days or weeks), subacute (followed by rapid deterioration over months), and chronic fashion (insidious at first with gradual worsening).^15,54,55 Early recognition of PS represents mainstay of the treatment because chronic forms are often resistant to therapy. Most of the PD patients with PS are not aware of lateral trunk deviation in the early stage.³⁵ At the beginning, only a slight tendency to lean on side can be observed while patient is sitting, with worsening during walking. A special phenomenon is “veering gait”, which denotes progressive deviation toward one side when patient is walking forward and backward with eyes closed. In advance stage, patients often experience debilitating pain, dyspnea, or unsteadiness leading to falls.

Probably, the most important thing when dealing with PS in PD patients is early recognition of this rare and incapacitating symptom, because appropriate management in acute or subacute phase can prevent chronic irreversible state.